Computer tomography image reconstruction

ABSTRACT

A method for reconstructing a Computer Tomography (CT) image is disclosed. The method may comprise: obtaining a X-ray projection data frame and a dynamic sensor information data frame, wherein the X-ray projection data frame may include a first timestamp indicating acquisition time of X-ray projection data and the dynamic sensor information data frame may include a second timestamp indicating acquisition time of dynamic sensor information data; extracting the first timestamp from the X-ray projection data frame and extracting the second timestamp from the dynamic sensor information data frame; searching X-ray projection data and dynamic sensor information data which may be acquired in same sampling period according to a first timestamp and a second timestamp; and reconstructing a CT image according to the searched X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Chinese Patent Application No. 201410817435.5, filed on Dec. 24, 2014, the entire contents of which are hereby incorporated by reference for all purposes.

BACKGROUND

The present invention relates to the technical field of medical imaging and, more particularly, to a Computer Tomography (CT) image reconstruction.

NEUSOFT MEDICAL SYSTEMS CO., LTD. (NMS), founded in 1998 with its world headquarters in China, is a leading supplier of medical equipment, medical IT solutions, and healthcare services. NMS supplies medical equipment with a wide portfolio, including CT, MRI, digital X-ray machines, Ultrasound, PET (Positron Emission Tomography), Linear Accelerators, and Biochemistry Analysers. Currently, NMS' products are exported to over 60 countries and regions around the globe, serving more than 5,000 renowned customers. NMS' latest successful developments, such as the 128 Multi-Slice CT Scanner System, Superconducting MRI, Linear Accelerator, and PET products, have led China to become a global high-end medical equipment producer. As an integrated supplier with extensive experience in large medical equipment, NMS is committed to the study of avoiding secondary potential harm caused by excessive X-ray irradiation to the subject during the CT scanning process.

BRIEF DESCRIPTION OF DRAWINGS

Features of the present disclosure are illustrated by way of example and not limited in the following figure(s), in which like numerals indicate like elements, in which:

FIG. 1A is a schematic diagram of an architecture of a CT scanning system, according to an example of the present disclosure;

FIG. 1B is a flowchart of a method for CT image reconstruction, according to an example of the present disclosure;

FIG. 2 is a schematic diagram of a sampling signal and inserting time of a first timestamp, according to an example of the present disclosure;

FIG. 3 is a schematic diagram of a CT scanning system receiving a cardiac cycle Electrocardiography (ECG) signal from an ECG monitoring device, according to an example of the present disclosure;

FIG. 4 is a flowchart of a method for cardiac CT image reconstruction, according to an example of the present disclosure;

FIG. 5 is a schematic diagram of a hardware structure of an apparatus for CT image reconstruction, according to an example of the present disclosure; and

FIG. 6 is a schematic diagram of function modules of control logic for reconstructing a CT image, according to an example of the present disclosure.

DETAILED DESCRIPTION

For simplicity and illustrative purposes, the present disclosure is described herein by referring mainly to an example thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be readily apparent however, that the present disclosure may be practiced without limitation to these specific details. In other instances, some methods and structures may not be described in detail so as not to unnecessarily obscure the present disclosure. As used herein, the terms “a” and “an” are intended to denote at least one of a particular element, the term “includes” means includes but not limited to, the term “including” means including but not limited to, and the term “based on” means based at least in part on.

In a typical CT scanning system, a data acquisition unit at a rotation end of the system may periodically acquire X-ray projection data according to a sampling period signal, wherein the rotation end may be a rotatable gantry device. The data acquisition unit may generate an X-ray projection data frame according to acquired X-ray projection data in one sampling period. At the same time, a sensor acquisition unit may acquire dynamic sensor information and transmit said dynamic sensor information to a data acquisition unit, wherein a dynamic sensor information may be the horizontal position of bed, ECG, etc. The data acquisition unit may insert the dynamic sensor information into the X-ray projection data frame according to a pre-defined frame format of an X-ray projection data frame. Then, the data acquisition unit may transmit the X-ray projection data frame with the dynamic sensor information to an image reconstruction unit at a stationary end through a data transmission slip ring. Finally, the image reconstruction unit may reconstruct a CT image according to an X-ray projection data frame with the dynamic sensor information.

In order to reconstruct a high quality CT image, the dynamic sensor information which may be acquired at the same sampling period with the X-ray projection data, may be transmitted to the data acquisition unit in the same sampling period. Therefore, it may be very important to control the transmission delay of the dynamic sensor information, especially for a dynamic sensor information with a large transmission delay. The dynamic sensor information with a large transmission delay may comprise the horizontal movement information of the scan bed.

In addition, the dynamic sensor information may usually be transmitted along with other information commands, such as a query command of the rotary end state, a response command of the data acquisition command, etc. The dynamic sensor may use the command transmission slip ring in order to transmit the dynamic sensor information and other information commands in multiplex. In general, a command transmission slip ring may be a brush contact structure. Thus, the signal transmission efficiency of the command transmission slip ring may not be too high, and the transmission delay of the command transmission slip ring may be very large. In addition, in order to ensure the command signal be transmitted in real-time, the priority of the command signal may be higher than that of the dynamic sensor information. Thus, the transmission delay of the dynamic sensor information may be increased. Additionally, the communication protocol of the command signal may have a response and retransmission mechanisms, particularly during the CT scanning period. When the command transmission slip ring may be affected by electromagnetic interference or mechanical vibration, it may cause command signal retransmitting and further increase the transmission delay of dynamic sensor information. Thus, the transmission delay of the dynamic sensor information may be unpredictable.

The transmission delay of the dynamic sensor information may be large and unpredictable as discussed briefly above. Such a delay may cause the dynamic sensor information to not be transmitted to the data acquisition unit in one sampling period. Additionally, the correspondence between the X-ray projection data frame and the dynamic sensor information acquired in the same sampling period may be deviated, thereby affecting the quality of the reconstructed CT image.

FIG. 1A is a schematic diagram of an architecture of a CT scanning system according to an example of the present disclosure. FIG. 1B is a flowchart of a method for CT image reconstruction according to an example of the present disclosure. The descriptions of blocks of FIG. 1B may be referenced with the components of FIG. 1A.

As shown in FIG. 1B, at block S11, the image reconstruction unit 140 may obtain an X-ray projection data frame and a dynamic sensor information data frame.

In this example, the X-ray projection data frame may include a first timestamp indicating acquisition time of the X-ray projection data, and the dynamic sensor information data frame may include a second timestamp indicating acquisition time of the dynamic sensor information data. Thus, the image reconstruction unit 140 may retrieve the X-ray projection data and the corresponding dynamic sensor information data according to a first timestamp of the X-ray projection data frame and a second timestamp of the dynamic sensor information data frame. Therefore, it may ensure the quality of the reconstruction image.

An X-ray projection data frame may include X-ray projection data acquired in one sampling period. A dynamic sensor information data frame may include dynamic sensor information data acquired in one pre-determined time period. In general, the pre-determined time period may not be greater than the sampling period. For example, the pre-determined time period may be less than or equal to the sampling period. Thus, in one sampling period, it may be possible to generate at least one dynamic sensor information data frame. For example, when the pre-determined time period may be much less than the sampling period, it may generate a plurality of dynamic sensor information data frames in one sampling period.

In addition, the length of the sampling period may usually be associated with the rotational speed of a rotatable gantry of the CT scanning system. For example, the higher the rotational speed may be, the shorter the sampling period may be.

According to an example, at block S11, obtaining the X-ray projection data frame may further comprise block S11 a 1 (not shown in FIG. 1B) and block S11 a 2 (not shown in FIG. 1B).

At block S11 a 1, the X-ray projection data frame may acquire X-ray projection data according to a sampling period signal and record acquisition time of the X-ray projection data.

Specifically, the data acquisition unit 110 at the rotation end may acquire X-ray projection data according to the sampling period signal and record acquisition time of the X-ray projection data.

According to one example, the X-ray projection data frame may record acquisition time of the X-ray projection data by a first counter 111. As shown in FIG. 1A, the first counter 111 may be provided in the data acquisition unit 110. The value of the first counter 111 may be incremented by 1 in each fixed time period. Thus, the count value of the first counter 111 may represent time. In general, the fixed time period may be less than the sampling period.

Further, when the data acquisition unit 110 receives a start scanning instruction from the main control unit 150, a first counter 111 may be activated. When the data acquisition unit 110 receives an end scanning instruction from the main control unit 150, the first counter 111 may be reset and turned off. As shown in FIG. 1A, scan instructions from the main control unit 150 may be transmitted to the data acquisition unit 110 via a slip ring 160, wherein the scan instructions may comprise the start scanning instruction and the end scanning instruction.

Further, it may latch up the value of a first counter 111 based on a rising edge of the sampling period signal. The latched value of the first counter 111 may be used to indicate an acquisition time of the X-ray projection data. FIG. 2 is a schematic diagram of a sampling period signal and an inserting time of a first timestamp according to an example of the present disclosure

At block S11 a 2, the data acquisition unit may generate an X-ray projection data frame according to X-ray projection data acquired in the same sampling period and corresponding acquisition time, wherein the acquisition time may be recorded into a timestamp field of the X-ray projection data frame as the first timestamp.

In general, the X-ray projection data frame may have a pre-defined frame format in which deploys a timestamp field. The data acquisition unit may record the acquisition time of the X-ray projection data into the timestamp field of the X-ray projection data frame as a first timestamp. At the same time, the data acquisition unit may generate an X-ray projection data frame according to the X-ray projection data which may be acquired in the same sampling period. Thus, the generated X-ray projection data frame may comprise X-ray projection data and acquisition time of the X-ray projection data.

Thereafter, the data acquisition unit 110 may transmit the generated X-ray projection data frame through a slip ring 130 to the image reconstruction unit 140.

According to an example, at block S11, obtaining the dynamic sensor information data frame may comprise block S11 b 1 (not shown in FIG. 1B) and block S11 b 2 (not shown in FIG. 1B).

At block S11 b 1, the data acquisition unit may acquire dynamic sensor information data and record acquisition time of the dynamic sensor information data.

Specifically, the sensor acquisition unit 120 may acquire dynamic sensor information data and record acquisition time of the dynamic sensor information data, wherein the dynamic sensor information data may be acquired by a dynamic monitoring equipment (not shown in FIG. 1A). For example, according to scan protocol settings of a CT scanning system, the sensor acquisition unit 120 may receive real-time dynamic sensor information data acquired by dynamic monitoring equipment. The sensor acquisition unit 120 may record receipt time of received dynamic sensor information data as the acquisition time of the received dynamic sensor information data.

Furthermore, in the CT scanning system of the present disclosure, the data amount of the dynamic sensor information data may be substantially less than that of the X-ray projection data. Thus, a relatively high frequency for acquiring the dynamic sensor information data may present advantages in subsequent processing in order to search X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period.

According to one example, sensor acquisition unit 120 may record acquisition time of the dynamic sensor information data by a second counter 121. As shown in FIG. 1A, the second counter 121 may be provided in the sensor acquisition unit 120. The value of a second counter 121 may be incremented by 1 in a fixed time period. Thus, the count value of the second counter 121 may represent time. In general, the fixed time period may be less than the sampling period.

Further, when the sensor acquisition unit 120 receives a start scanning instruction from the main control unit 150, the second counter 121 may be activated. When the sensor acquisition unit 120 receives an end scanning instruction from the main control unit 150, the second counter 121 may be reset and subsequently turned off. As shown in FIG. 1A, scan instructions from the main control unit 150 may be directly transmitted to the sensor acquisition unit 120, wherein the scan instructions may comprise a start scanning instruction and an end scanning instruction.

At block S11 b 2, the sensor acquisition unit may generate a dynamic sensor information data frame according to dynamic sensor information data acquired in the same pre-determined time period and corresponding acquisition time, wherein the acquisition time may be recorded into a timestamp field of the dynamic sensor information data frame as a second timestamp.

In general, the dynamic sensor information data frame may also comprise a pre-defined frame format in which deploys a timestamp field. The sensor acquisition unit may record the acquisition time of the dynamic sensor information data into a timestamp field of the dynamic sensor information data frame as a second timestamp. At the same time, the sensor acquisition unit may generate a dynamic sensor information data frame according to the dynamic sensor information data which may be acquired in the same pre-determined time period. Thus, the generated dynamic sensor information data frame may comprise the dynamic sensor information data and the acquisition time of the dynamic sensor information data.

In addition, according to the aforementioned descriptions, a pre-determined time period may usually not be greater than one sampling period. Thus, in one sampling period, the sensor acquisition unit may acquire at least one set of dynamic sensor information data. Therefore, it may generate at least one dynamic sensor information data frame in one sampling period.

Thereafter, the sensor acquisition unit 120 may transmit a generated dynamic sensor information data frame to an image reconstruction unit 140.

At block S12, the image reconstruction unit may extract a first timestamp from the X-ray projection data frame and extract a second timestamp from a dynamic sensor information data frame.

For example, the image reconstruction unit 140 may extract a first timestamp from the X-ray projection data frame according to the frame format of the X-ray projection data frame, and extract a second timestamp from the dynamic sensor information data frame according to the frame format of the dynamic sensor information data frame.

At block S13, the image reconstruction unit may search X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period according to a first timestamp and a second timestamp.

According to a first timestamp and a second timestamp, the sensor acquisition unit may decide the acquisition time of the X-ray projection data and the acquisition time of the dynamic sensor information data, respectively. An image reconstruction unit 140 may search X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period according to a timestamp and a second timestamp.

For example, the sensor acquisition unit may use a first counter 111 and a second counter 121 to record the acquisition time of the X-ray projection data and the acquisition time of the dynamic sensor information data, respectively. The first counter 111 and the second counter 121 may be activated when receiving a start scanning instruction. Since the delays of scan instructions being transmitted to the first counter 111 and the second counter 121 may both be fixed, the sensor acquisition unit may previously calculate the difference between the delay of the scan instruction being transmitted to a first counter 111 and the delay of the scan instruction being transmitted to a second counter 121 as a compensation amount. Then, the sensor acquisition unit may use the compensation amount to calibrate an offset between the acquisition time of the X-ray projection data recorded by a first counter 111 and the acquisition time of the dynamic sensor information data recorded by a second counter 121. The image reconstruction unit 140 may search X-ray projection data and dynamic sensor information data which may be acquired in same sampling period in accurate.

In block S14, the image reconstruction unit 140 may reconstruct a CT image according to the searched X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period.

In the process of reconstructing a CT image, the X-ray projection data may be dynamically compensated according to the dynamic sensor information data which may be acquired in the same sampling period with the X-ray projection data, so that a reconstructed CT image may be more clear than before.

The image reconstruction unit 140 may use the timestamps provided in order to implement an accurate search for X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period, so as to avoid any influence from transmission delay of the dynamic sensor information data. Nevertheless, whether the X-ray projection data is received earlier or later than the dynamic sensor information data, the image reconstruction unit may find X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period, dynamically compensate the X-ray projection data according to the dynamic sensor information data acquired in the same sampling period with the X-ray projection data, and thus reconstruct a substantially clearer CT image.

FIG. 3 is a schematic diagram of an example CT scanning system receiving a cardiac cycle ECG signal from an ECG monitoring device and a cardiac CT image reconstruction according to an example of the present disclosure. In general, in order to reconstruct a clear cardiac CT image, it may be beneficial to adopt an X-ray projection data frame of which the acquisition time may correspond to a specific time interval. In the specific time interval, shown as dashed lines in FIG. 3 during one cardiac cycle period, the heart may have remained in a relative stationary state.

FIG. 4 is a flowchart of a method for cardiac CT image reconstruction according to an example of the present disclosure. As shown in FIG. 4, the method may comprise blocks S41 to S48.

At block S41, the data acquisition unit 110 of the CT scanning system may acquire X-ray projection data, record acquisition time of the X-ray projection data, and generate an X-ray projection data frame according to the X-ray projection data and corresponding acquisition time, wherein the acquisition time may be recorded into a timestamp field of the X-ray projection data frame as a first timestamp.

At block S42, the sensor acquisition unit 120 of the CT scanning system may receive a cardiac cycle ECG signal from an ECG monitoring device.

At block S43, the sensor acquisition unit 120 of the CT scanning system may generate a dynamic sensor information data frame according to the cardiac cycle ECG signal and other dynamic sensor information data, and insert a second timestamp and a peak identifier (R) into the dynamic sensor information data frame, wherein a second timestamp may represent acquisition time of the cardiac cycle ECG signal and a peak identifier (R) may indicate whether the signal is an ECG signal or not.

According to one example, before generating a dynamic sensor information data frame, the sensor acquisition unit may convert a cardiac cycle ECG signal from an analogue domain to a digital domain, and may generate the dynamic sensor information data frame according to a digital cardiac cycle ECG signal.

At block S44, the image reconstruction unit 140 of the CT scanning system may obtain an X-ray projection data frame and a dynamic sensor information data frame.

At block S45, when the peak identifier R of an ECG signal in a dynamic sensor information data frame is detected to be valid, the image reconstruction unit 140 may obtain a first time (T1) from a start scanning time to a peak identifier R as shown in FIG. 3.

At block S46, according to characteristics of an ECG signal and a first time T1, the image reconstruction unit may obtain a second time (T2) from a start scanning time to a starting time of a relative stationary state of the heart in a cardiac cycle period.

At block S47, the image reconstruction unit may search the first timestamp which may be nearest to a second time T2 as a starting point of the acquisition time of the X-ray projection data, thus the X-ray projection data corresponding to the searched first timestamp may be acquired in a relative stationary state of the heart in a cardiac cycle period. By using a first timestamp and a second time stamp, the image reconstruction unit may select, based on the searched starting point of the acquisition time, the X-ray projection data and the dynamic sensor information data which may correspond to a relative stationary state of the heart in the cardiac cycle period. For example, a relative stationary state of the heart in the cardiac cycle period may be the time interval shown as the dashed lines in FIG. 3.

At block S48, the image reconstruction unit may use the X-ray projection data and the dynamic sensor information data corresponding to a relative stationary state of the heart in the cardiac cycle period in order to reconstruct a cardiac CT image.

The present disclosure also provides an apparatus for CT image reconstruction. FIG. 5 is a schematic diagram of the hardware structure of the apparatus for CT image reconstruction according to an example of the present disclosure. As shown in FIG. 5, an apparatus for CT image reconstruction may comprise a processor 51, a storage medium 52, an internal bus 53, and an interface 54. The storage medium 52 and the interface 54 may be accessible by the processor 51 through an internal bus 53.

The storage medium 52 may be a non-volatile memory or storage media including, by way of example, semiconductor memory devices, such as EPROM, EEPROM, DRAM and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks.

Further, the storage medium 52 may store machine readable instructions corresponding to a control logic 60 for reconstructing CT image. FIG. 6 is a schematic diagram of function modules of the control logic 60 for reconstructing CT images according to an example of the present disclosure. As shown in FIG. 6, the control logic 60 for reconstructing CT image may comprise an acquisition module 61, an extraction module 62, a search module 63, and a reconstruction module 64.

The acquisition module 61 may obtain the X-ray projection data frame and the dynamic sensor information data frame, wherein the X-ray projection data frame may comprise a first timestamp indicating acquisition time of X-ray projection data and the dynamic sensor information data frame which may comprise a second timestamp indicating acquisition time of dynamic sensor information data. The X-ray projection data comprised in an X-ray projection data frame may be acquired in one sampling period, and the dynamic sensor information data comprised in a dynamic sensor information data frame may be acquired in one pre-determined time period, and the pre-determined time period may not be longer in duration than a sampling period.

The extraction module 62 may extract the first timestamp from an X-ray projection data frame and extract a second timestamp from a dynamic sensor information data frame.

The search module 63 may search X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period according to a first timestamp and a second timestamp.

The reconstruction module 64 may reconstruct a CT image according to the searched X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period.

According to one example, the acquisition module 61 may include a data acquisition sub-module 611, an X-ray projection data frame generation sub-module 612, a data receiving sub-module 613, and a dynamic sensor information data frame generation sub-module 614.

The data acquisition sub-module 611 may be used to acquire X-ray projection data according to a sampling period signal and record acquisition time of the X-ray projection data.

The X-ray projection data frame generation sub-module 612 may be used to generate an X-ray projection data frame according to the X-ray projection data acquired in the same sampling period and the corresponding acquisition time, wherein the acquisition time may be recorded into a timestamp field of the X-ray projection data frame as a first timestamp

Furthermore, the data acquisition sub-module 611 may use a first counter to record the acquisition time of the X-ray projection data, wherein the value of the first counter may be incremented by 1 in a fixed time period and the fixed time period may be shorter in duration than the sampling period.

The data receiving sub-module 613 may be used to receive acquired dynamic sensor information data and record acquisition time of the dynamic sensor information data.

The dynamic sensor information data frame generation sub-module 614 may be used to generate a dynamic sensor information data frame according to the dynamic sensor information data acquired in a pre-determined time period and the corresponding acquisition time, wherein the acquisition time may be recorded into a timestamp field of the dynamic sensor information data frame as the second timestamp.

Furthermore, the data receiving sub-module 613 may use a second counter to record the acquisition time of the dynamic sensor information data, wherein the value of a second counter may be incremented by 1 in a fixed time period and the fixed time period may be shorter in duration than the sampling period.

The following technology may be implemented in software which is described the operation of the control logic 60 for reconstructing a CT image. The control logic 60 for reconstructing a CT image may be the machine readable instructions stored in the storage medium 52. The processor 51 of the apparatus for CT image reconstruction may read the instructions of corresponding modules of the control logic 60 for reconstructing a CT image stored in the storage medium 52 and may execute the instructions.

The instructions executed by the processor 51 may cause the processor 51 to perform the following operations.

The processor 51 may obtain an X-ray projection data frame and a dynamic sensor information data frame, wherein the X-ray projection data frame may comprise a first timestamp indicating acquisition time of X-ray projection data and the dynamic sensor information data frame may comprise a second timestamp indicating acquisition time of dynamic sensor information data.

The processor 51 may extract a first timestamp from the X-ray projection data frame and extract a second timestamp from the dynamic sensor information data frame.

The processor 51 may search X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period according to a first timestamp and a second timestamp.

The processor 51 may reconstruct a CT image according to the searched X-ray projection data and dynamic sensor information data which may be acquired in the same sampling period.

The X-ray projection data comprised in a X-ray projection data frame may be acquired in a sampling period, the dynamic sensor information data comprised in a dynamic sensor information data frame may be acquired in a pre-determined time period, and the pre-determined time period may be less than or equal to the sampling period.

According one example of present disclosure, when obtaining the X-ray projection data frame, the instructions executed by the processor 51 may cause the processor 51 to perform the following operations.

The processor 51 may acquire X-ray projection data according to the sampling period signal and may record acquisition time of the X-ray projection data.

The processor 51 may generate an X-ray projection data frame according to X-ray projection data acquired in the same sampling period and corresponding acquisition time, wherein the acquisition time may be recorded into a timestamp field of the X-ray projection data frame as a first timestamp.

Furthermore, when recording the acquisition time of the X-ray projection data, the instructions executed by the processor 51 may cause the processor 51 to perform the following operations. The processor 51 may use a first counter to record the acquisition time of the X-ray projection data, wherein the value of a first counter may be incremented by 1 in a fixed time period and the fixed time period may be shorter in duration than the sampling period.

According one example of present disclosure, for obtaining of the dynamic sensor information data frame, the instructions executed by the processor 51 may cause the processor 51 to perform the following operations.

The processor 51 may acquire dynamic sensor information data and record acquisition time of the dynamic sensor information data.

The processor 51 may generate a dynamic sensor information data frame according to dynamic sensor information data acquired in the same pre-determined time period and corresponding acquisition time, wherein the acquisition time may be recorded into a timestamp field of the dynamic sensor information data frame as a second timestamp.

Furthermore, when recording the acquisition time of the dynamic sensor information data, the instructions executed by the processor 51 may cause the processor 51 to perform the following operations. The processor 51 may use a second counter to record the acquisition time of the dynamic sensor information data, wherein the value of the second counter may be incremented by 1 in a fixed time period and the fixed time period may be shorter in duration than the sampling period.

The above are only preferred examples of the present disclosure and are not intended to limit the disclosure within its spirit and principles. Any changes made, equivalent replacements, or improvement in the protection of the present disclosure should be contained within its range.

The methods, processes and units described herein may be implemented by hardware (including hardware logic circuitry), software or firmware or a combination thereof. The term ‘processor’ is to be interpreted broadly to include a processing unit, ASIC, logic unit, or programmable gate array etc. The processes, methods and functional units may all be performed by the one or more processors; reference in this disclosure or the claims to a ‘processor’ should thus be interpreted to mean ‘one or more processors’.

Further, the processes, methods and functional units described in this disclosure may be implemented in the form of a computer software product. The computer software product may be stored in a storage medium and may comprise a plurality of instructions for making a processor to implement the methods recited in the examples of the present disclosure.

The figures are only illustrations of an example, wherein the units or procedure shown in the figures may not be necessarily essential for implementing the present disclosure. Those skilled in the art will understand that the units in the device in the example may be arranged in the device in the examples as described, or may be alternatively located in one or more devices different from that in the examples. The units in the examples described may be combined into one module or further divided into a plurality of sub-units.

Although the flowcharts described show a specific order of execution, the order of execution may differ from that which is depicted. For example, the order of execution of two or more blocks may be changed relative to the order shown. Also, two or more blocks shown in succession may be executed concurrently or with partial concurrence. All such variations are within the scope of the present disclosure.

Throughout the present disclosure, the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. 

The invention claimed is:
 1. A method for reconstructing a Computer Tomography (CT) image comprising: obtaining an X-ray projection data frame and a dynamic sensor information data frame, wherein the X-ray projection data frame has a first timestamp indicating acquisition time of X-ray projection data and the dynamic sensor information data frame has a second timestamp indicating acquisition time of dynamic sensor information data; extracting the first timestamp from the X-ray projection data frame and extracting the second timestamp from the dynamic sensor information data frame; searching X-ray projection data and dynamic sensor information data which are acquired in a same sampling period according to the first timestamp and the second timestamp; and reconstructing a CT image according to the searched X-ray projection data and dynamic sensor information data which are acquired in the same sampling period.
 2. The method according to claim 1, wherein the X-ray projection data of the X-ray projection data frame is acquired in a sampling period, and the dynamic sensor information data of the dynamic sensor information data frame is acquired in a pre-determined time period, wherein the pre-determined time period is less than or equal to the sampling period.
 3. The method according to claim 2, wherein obtaining the dynamic sensor information data frame comprises: acquiring the dynamic sensor information data and recording the acquisition time of the dynamic sensor information data; and generating the dynamic sensor information data frame according to the dynamic sensor information data acquired in the pre-determined time period and corresponding acquisition time, wherein the acquisition time is recorded into a timestamp field of the dynamic sensor information data frame as the second timestamp.
 4. The method according to claim 3, wherein recording the acquisition time of the dynamic sensor information data comprises: recording the acquisition time of the dynamic sensor information data by a second counter of which value is incremented with 1 in a fixed time period, wherein the fixed time period is less than the sampling period.
 5. The method according to claim 1, wherein obtaining the X-ray projection data frame comprises: acquiring the X-ray projection data according to a sampling period signal and recording the acquisition time of the X-ray projection data; and generating the X-ray projection data frame according to the X-ray projection data acquired in the same sampling period and corresponding acquisition time, wherein the acquisition time is recorded into a timestamp field of the X-ray projection data frame as the first timestamp.
 6. The method according to claim 5, wherein recording the acquisition time of the X-ray projection data comprises: recording the acquisition time of the X-ray projection data by a first counter of which value is incremented with 1 in a fixed time period, wherein the fixed time period is less than the sampling period.
 7. An apparatus for computer tomography (CT) image reconstruction, comprising a processor, wherein by reading and executing machine readable instructions of control logic for reconstructing a CT image stored in a storage medium, the processor is caused to: obtain an X-ray projection data frame and a dynamic sensor information data frame, wherein the X-ray projection data frame has a first timestamp indicating acquisition time of X-ray projection data and the dynamic sensor information data frame has a second timestamp indicating acquisition time of dynamic sensor information data; extract the first timestamp from the X-ray projection data frame and extract the second timestamp from the dynamic sensor information data frame; search the X-ray projection data and the dynamic sensor information data which are acquired in a same sampling period according to the first timestamp and the second timestamp; and reconstruct a CT image according to the searched X-ray projection data and dynamic sensor information data which are acquired in the same sampling period.
 8. The apparatus according to claim 7, wherein the X-ray projection data of the X-ray projection data frame is acquired in a sampling period, and the dynamic sensor information data of the dynamic sensor information data frame is acquired in a pre-determined time period, wherein the pre-determined time period is less than or equal to the sampling period.
 9. The apparatus according to claim 8, wherein the machine readable instructions are further to cause the processor to: acquire the dynamic sensor information data and recording the acquisition time of the dynamic sensor information data; and generate the dynamic sensor information data frame according to the dynamic sensor information data acquired in the same pre-determined time period and corresponding acquisition time, wherein the acquisition time is recorded into a timestamp field of the dynamic sensor information data frame as the second timestamp.
 10. The apparatus according to claim 9, wherein the machine readable instructions are further to cause the processor to: record the acquisition time of the dynamic sensor information data by a second counter of which value is incremented with 1 in a fixed time period, wherein the fixed time period is less than the sampling period.
 11. The apparatus according to claim 7, wherein the machine readable instructions are further to cause the processor to: acquire the X-ray projection data according to a sampling period signal and recording the acquisition time of the X-ray projection data; and generate the X-ray projection data frame according to the X-ray projection data acquired in the same sampling period and corresponding acquisition time, wherein the acquisition time is recorded into a timestamp field of the X-ray projection data frame as the first timestamp.
 12. The apparatus according to claim 11, wherein the machine readable instructions are further to cause the processor to: record the acquisition time of the X-ray projection data by a first counter of which value is incremented with 1 in a fixed time period, wherein the fixed time period is less than the sampling period. 